基于Java8 Stream API实现数据抽取收集

class Order{
  String orderSeq;
  String status;
  double totalPrice;
  String expressInfo;
  // 省略get,set及hashCode等方法
} 

class ExpressInfo{
  String orderSeq;
  String expressName;
  String expressNo;
  String createTime;
  String statusInfo;
  // 省略get,set及hashCode等方法
}

  List<Order> orderList = getOrderList();
  // 抽取 订单号
  List<String> orderSeqList = new ArrayList<>();
  for (Order order : orderList) {
    orderSeqList.add(order.getOrderSeq());
  }

// 调用远程服务，
List<ExpressInfo> expressInfos = RpcGetExpressInfoBatch(orderSeqList);
// 组装 订单-快递 关系map
Map<String,String> orderExpressMap = new HashMap<>();
for(ExpressInfo e: expressInfos){
  orderExpressMap.put(e.getOrderSeq(),e.getStatusInfo());
}

for(Order order:orderList){
  String expressInfo = orderExpressMap.get(order.getOrderSeq());
  order.setExpressInfo(expressInfo);
}

// 获取列表
List<Order> orderList = getOrderList();
// 抽取单号
List<String> orderSeqs = orderList.stream()
    .map(Order::getOrderSeq)
    .collect(Collectors.toList());

List<ExpressInfo> expressInfos = RpcGetExpressInfoBatch(orderSeqList);
Map<String,String> orderExpressMap =expressInfos.stream()
    .collect(Collectors.toMap(ExpressInfo::getOrderSeq,ExpressInfo::getStatusInfo));

orderList.stream().forEach(o -> o.setExpressInfo(orderExpressMap.get(o.getOrderSeq())));